Scottish actor Alan Cumming, who has homes in Edinburgh and New York, has launched a Twitter campaign entitled Project #goforitScotland, for "Scots and friends of Scotland around the UK and the world".
Rhys Ifans, actor and Welsh language campaigner, has lent his support alongside Joe Dempsie and James Cosmo, both currently starring in Game Of Thrones, X Men actor Brian Cox and Plaid Cymru leader Leanne Wood.
Ifans, star of Notting Hill and Harry Potter, said: "I wish you the best of luck in September for a Yes vote. Go for it Scotland, I'm behind you 100%."
Cox, rector of Dundee University and the first Hollywood Hannibal Lecter, said: "It's time for independence, we have an opportunity to re-energise these islands, democratically, economically and politically, creating a more equal society."
Cosmo, who featured in Braveheart and Troy, said: "The people of Scotland have got what it takes to be a successful independent Scotland. We need to go for it."
Ms Wood said: "The exciting debate on Scotland's future gives Wales an opportunity to set out its own ambitions for the powers we need, particularly job creation powers."
The campaign was promoted at an international press briefing at the SNP conference in Aberdeen, hosted by deputy leader Nicola Sturgeon and Westminster leader Angus Robertson.
Rebranded the "Scottish International Party" for the session, they addressed journalists from countries including Germany, Netherlands, China, Japan, Sweden and Spain, with particularly broad representation from Catalonia which has also has a strong separatist movement.
Mr Robertson said: "We are having to manage an unprecedented level of media interest.
"We have started a weekly briefing for international media in London by geography, starting this week with the German language media, and every week from now on in the run-up to the campaign we will be holding further events."
Ms Sturgeon said: "Whatever side of this debate you're on, the opportunity for Scotland to be in the spotlight, to have quite literally the eyes of the world upon us, is a thoroughly good thing.
"We are seeing today the launch of a social media campaign, Go For It Scotland, on Twitter by Alan Cumming, an opportunity for people who care about, have an interest in, love Scotland, perhaps came from Scotland, but don't have a vote, to show their support."